Apparatus for casting ceramic articles

ABSTRACT

An automatic slip dispensing head comprises a slip dispensing nozzle which is lowered into a filling position from a retracted position, conductive probes between which the slip dispensed completes a circuit when a desired depth of slip has been dispensed into a mould, and a probe cleaning brush which operates to clean the probes between each filling operation.

United States Patent 1 Gough 51March 13, 1973 1 APPARATUS FOR CASTING CERAMIC ARTICLES [75] Inventor: George Terah Gough, Newcastle,

England [73] Assignee: Gouch and Company (l-Ianley) Limited, Hanley, Stoke-on-Trent,

England 22 Filed: July9, 1971 21 Appl.No.: 161,216

[52] (1.8. CI ..425/147, 425/225 [51] Int. Cl ..B28c 7/16 [58] Field of Search ..425/145, 147, 225; 15/2565 [56] References Cited UNITED STATES PATENTS McCann ..425/147 Diederichs ..l5/256.5

3,617,555 11/1971 Ginsburgh ..15/256.5 UX

3,662,437 5/1972 Long ..425/147 3,448,496 6/1969 Arnold et a1. .....425/167 3,416,203 12/1968 Ozenne et a1 ..425/96 3,448,497 6/1969 Arnold et al ..425/225 X 3,187,362 6/1965 Garrett ..15/210 R Primary Examiner-J. Spencer Overholser Assistant Examiner-B. D. Tobor Att0rneyDonald M. Wight et a1.

57 1 ABSTRACT An automatic slip dispensing head comprises a slip dispensing nozzle which is lowered into a filling position from a retracted position, conductive probes between which the slip dispensed completes a circuit when a desired depth of slip has been dispensed into a mould, and a probe cleaning brush which operates to clean the probes between each filling operation.

8 Claims, 4 Drawing Figures PATENTEUHARHIQB ,720,494

SHEET 30F 3 1 M mma APPARATUS FOR CASTING CERAMIC ARTICLES This invention relates to casting machines for the ceramic industry.

Cast ceramic ware is conventionally produced by filling an absorbent plaster of paris mould with liquid slip, allowing the mould to absorb moisture from the slip so as to partially solidify the slip nearest the walls of the mould, pouring off the excess slip, drying the moulding, dismantling the moulds and removing the mouldings, and drying the moulds for reuse.

Casting machines are known comprising an endless conveyor from which is suspended a number of trays to which moulds can be secured for transport through the various stages listed above. Thus at one end of the upper run, assembled moulds are loaded onto trays, which then pass through an oven in which they are dried before being filled with slip from filling heads on a special trolley movable over a filling zone of the conveyor. During the remainder of the upper run and the first part of the lower run the slip remains in the moulds, the trays then being inverted to pour off excess slip which is recycled. The trays, still inverted, then pass back through the oven before being reverted and returning to the upper run for the moulds to be removed and replaced by empty moulds.

Hitherto the filling of the moulds with slip has had to be controlled by an operative who moves the trolley over the moulds and controls the flow of slip so that each mould is filled to the correct level and although efforts have been made to automate this process, the applicant is not aware that any fully satisfactory automatic filling head has been developed for this purpose.

The object of the present invention is to provide apparatus for automatically filling the moulds to the correct level.

Much of the difficulty of providing such apparatus centers around the problem of sensing the level of slip in the moulds so as to control the supply of slip. Numerous level sensing devices are known, many of them highly sophisticated, but experiment has not shown any of them to be really satisfactory in the present application. The applicant has now discovered a comparatively simple and cheap arrangement which proves thoroughly reliable in practice.

According to the invention, apparatus for dispensing slip to a mould in a ceramic casting machine comprises a slip reservoir, a slip dispensing nozzle, a shut off valve provided in a tube connected between the reservoir and the nozzle, and level sensing means adapted to sense the level of slip in a mould placed beneath said nozzle and to control the shut off valve in response thereto, characterized in that the level sensing means comprise two conductive probes associated with the nozzle and arranged so that, when the nozzle is positioned for filling a mould, a circuit will be completed between the probes by the slip dispensed into the mould when this reaches a desired level, the nozzle being supported in a frame for movement relative thereto between said filling position and a withdrawn position, probe cleaning means being carried by the frame so as to act on said probes during said each movement cycle.

A preferred embodiment of the described with reference to drawings in which:

invention is the accompanying FIG. 1 is a front elevation of slip dispensing apparatus,

FIG. 2 is a vertical cross-section through the apparatus, on the line II II in FIG. 1,

FIG. 3 is a detail showing a valve to admit slip to the apparatus, and

FIG. 4 is a section of detail on the line IV IV in FIG. 1.

The apparatus comprises a wheeled gantry comprising side frames 2 and 4 supported by wheels 6 and interconnected by cross members 8, 10 and 12. This gantry is, when the apparatus is in use, supported by its wheels 6 on rails forming part of a ceramic casting machine, the rails enabling the gantry to be positioned above moulds to be filled.

Supported on the cross members 8 is a slip tank 14, provided with a probe unit 16 operating an indicator showing the level of slip in the tank, a drain cock 17, a valved hose connection 18 through which water may be admitted in order to flush the tank when cleaning is required, and a valve assembly 20 through which slip is admitted to the tank from a further reservoir (not shown). In order to avoid the danger of blockage due to slip coagulating in the mechanism of the valve, this is of the type (see FIG. 3) in which an external actuator (in the example shown an electro pneumatic actuator 22 which is mounted on a frame 24 supporting the end unions 26 of the valve) acts through its piston 28 to compress a flexible pipe section 30 against an anvil, thus cutting off the supply of slip to the tank.

Slip passes from the tank 14 through normally open valves 32 and flexible pipes 34 to further valves 36 controlling the discharge of slip through nozzles 38. The valves 36 are controlled by pneumatic cylinders 40, and the assemblies formed by each cylinder 40 and valve 36 are mounted on plates 42 carried by a bracket 44 which forms a component of a linkage operative to reciprocate the assemblies carried by the plates 42 upwardly and downwardly. This linkage further comprises swing links 46, connecting rods 48, and coupling rods 50, the reciprocatory motion applied to the plates 42 being derived from part rotary motion of a shaft 52 by means of cranks 54. The shaft 52 is driven through a sprocket wheel 56 by means of a chain 58 from a geared reversible motor 60. Thus the motor 60 can be operated to cause the assemblies of cylinders 40, valves 36 and nozzles 38 to execute a reciprocatory upward and downward movement between a position in which metallic probes 62, a pair of which are carried by each valve 36, are located in the mouth of a mould situated beneath the gantry with the lower ends of the probes 62 extending downwardly to the level to which the moulds are intended to be filled with slip. At the other end of the reciprocatory movement, the valves 36 together with their associated nozzles 38 and probes 62 are and 4 respectively. Springs 76 act on the links 74 so as to maintain the follower 66 in contact with the cam 64. The lower ends of the links 74 are connected by the rods 78 to a tray 80 mounted for horizontal sliding movements by means of channel section members 82 carried by the side frames 2 and 4. Extending upwardly from the tray 80 is a brush 84.

The cam 64 is so set on the shaft 52 that as the shaft rotates (anticlockwise as seen in FIG. 4) from the position shown, the follower leaves the lobe of the cam, and the tray moves from the position shown in FIG. 2 towards the right, causing the brush 84 to wipe the probes 62 and the tray 80 to be moved clear of the valves 36 so as not to obstruct their downward movement. Thus before each downward movement of the valves 36, the probes are cleaned of slip adhering to them by means of the brush 84, the tray 80 serving to catch slip removed from the probes by the brush or dripping from the probes 62 or the nozzle 38 between filling operations.

In operation, a row of moulds secured in a suitable tray appropriate to the type of conveyor utilized in the casting machine is moved beneath the gantry so that the filling openings of the moulds are beneath the nozzles 38. It should be noted that the plates 42 are secured to the bracket 44 by means of winged screws 86 passing through slots 88 in the bracket so as to enable the lateral position of the plates 42 and the valves 36 carried by them to be adjusted in accordance with the spacing of the moulds in the tray. A peg 90 adapted to engage with holes provided in the track on the casting machine may be used to provide longitudinal location of the apparatus relative to the moulds.

Assuming the apparatus to be in the condition shown in FIGS. 1 and 2, the arrival of the moulds in the appropriate position beneath the gantry operates a limit switch (not shown) operative to start the motor 60, thus causing the cranks 54 to move out of their top dead center position and to lower the bracket 44 and thus the valves 36. In the meanwhile, the cam 64 is rotated so that its lobe disengaged the roller follower 66 as shown in FIG. 4, causing the tray 80 and the brush 84 to be moved from beneath the valve 36, during which movement the brush 84 wipes the probes 62.

The valves 36 are lowered until the nozzles 38 are adjacent the filling orifices of the moulds, with the probes 62 extending downwardly into these orifices to the level to which it is desired that the moulds be filled with slip. The extent to which the valve 36 are lowered is controlled by a limit switch 92 operated by a further cam 94 on the shaft 52, the relative positioning of the components of this assembly being adjusted to suit the moulds in use. This limit switch when actuated turns off the motor 60, and actuates the pneumatic cylinders 40 thus opening the valves 36 and permitting slip to enter the moulds through the nozzles 38. When the slip in a mould reaches the desired level, it contacts the probes 62 and completes an electrical circuit between them, the two probes 62 associated with each valve, which are electrically insulated from each other, being connected to a suitable relay circuit effective to operate the associated cylinder 40 so as to turn off the associated valve 36 and discontinue the supply of slip to that mould. Actuation of the limit switch 92 is also effective to start a timer, which, after a period has elapsed sufficient to allow filling of all the moulds to have been completed, restarts the motor in the reverse direction so as to retract the valves 36 from the mould. This reverse movement also rotates the cam 64 in the reverse direction so as to permit the tray and the brush 84 to return to their original positions, the brush wiping the probes 62 during this return movement.

Although in the apparatus described slip passes from the slip tank to the nozzles under the influence of gravity, it is possible, and with certain slip may indeed be necessary to introduce a slip pump between the tank and each nozzle. This may conveniently be of the peristaltic type comprising, for example, a rotor carrying a number of peripheral rollers which mangle the pipe 34 against an arcuate anvil thus urging the slip along the pipe whilst obviating any risk of blockage in the pump.

What I claim is:

1. Apparatus for dispensing slip to a mould in a ceramic casting machine comprising a slip reservoir, a slip dispensing nozzle, a shut off valve provided in a tube connected between the reservoir and the nozzle, and level sensing means adapted to sense the level of slip in a mould placed beneath said nozzle and to control the shut off valve in response thereto, characterized in that the level sensing means comprise two conductive probes associated with the nozzle and arranged so that, when the nozzle is positioned for filling a mould, a circuit will be completed between the probes by the slip'dispensed into the mould when this reaches a desired level, the nozzle being supported in a frame for vertical movement relative thereto between said filling position and a withdrawn position, and probe cleaning means being mounted by the frame for back and forth movement beneath said nozzle so as to act on said probes during said each movement cycle, means being provided for reciprocating said probe cleaning means and said nozzle in timed relationship.

2. Apparatus according to claim 1, wherein the extent of the vertical movement of the nozzle is adjustable.

3. Apparatus according to claim 2, wherein the driving means for the nozzle and the cleaning means are linkages deriving drive from a common shaft.

4. Apparatus according to claim 3, wherein the shaft is driven by a reversible motor.

5. Apparatus according to claim 4, wherein the probe cleaning means comprises a brush.

6. Apparatus according to claim 5, wherein the probe cleaning means further comprises a driptray mounted beneath the brush.

7. Apparatus according to claim 1, wherein the probe cleaning means comprises a brush.

8. Apparatus according to claim 7, wherein the brush is mounted above a driptray.

* t i t 

1. Apparatus for dispersing slip to a mould in a ceramic casting machine comprising a slip reservoir, a slip dispensing nozzle, a shut off valve provided in a tube connected between the reservoir and the nozzle, and level sensing means adapted to sense the level of slip in a mould placed beneath said nozzle and to control the shut off valve in response thereto, characterized in that the level sensing means comprise two conductive probes associated with the nozzle and arranged so that, when the nozzle is positioned for filling a mould, a circuit will be completed between the probes by the slip dispensed into the mould when this reaches a desired level, the nozzle being supported in a frame for vertical movement relative thereto between said filling position and a withdrawn position, and probe cleaning means being mounted by the frame for back and forth movement beneath said nozzle so as to act on said probes during said each movement cycle, means being provided for reciprocating said probe cleaning means and said nozzle in timed relationship.
 1. Apparatus for dispersing slip to a mould in a ceramic casting machine comprising a slip reservoir, a slip dispensing nozzle, a shut off valve provided in a tube connected between the reservoir and the nozzle, and level sensing means adapted to sense the level of slip in a mould placed beneath said nozzle and to control the shut off valve in response thereto, characterized in that the level sensing means comprise two conductive probes associated with the nozzle and arranged so that, when the nozzle is positioned for filling a mould, a circuit will be completed between the probes by the slip dispensed into the mould when this reaches a desired level, the nozzle being supported in a frame for vertical movement relative thereto between said filling position and a withdrawn position, and probe cleaning means being mounted by the frame for back and forth movement beneath said nozzle so as to act on said probes during said each movement cycle, means being provided for reciprocating said probe cleaning means and said nozzle in timed relationship.
 2. Apparatus according to claim 1, wherein the extent of the vertical movement of the nozzle is adjustable.
 3. Apparatus according to claim 2, wherein the driving means for the nozzle and the cleaning means are linkages deriving drive from a common shaft.
 4. Apparatus according to claim 3, wherein the shaft is driven by a reversible motor.
 5. Apparatus according to claim 4, wherein the probe cleaning means comprises a brush.
 6. Apparatus according to claim 5, wherein the probe cleaning means further comprises a driptray mounted beneath the brush.
 7. Apparatus according to claim 1, wherein the probe cleaning means comprises a brush. 